P6: Molecules and Matter

Question 1

What is internal energy?

Answer 1

The sum of the potential energy and kinetic energy of all the particles that make up a system.
Potential energy - due to the forces between particles and the bonds between atoms in a molecule

Question 2

Which state has the highest internal energy?

Answer 2

Gas

Question 3

What is a physical change?

Answer 3

Reversible changes - when a material reverts back it maintains its original properties

Question 3

What is evaporation?

Answer 3

When the particles on the surface of a liquid turn into a gas

Question 4

What is specific latent heat?

Answer 4

The energy needed for 1kg of a substance to change state

Question 5

Why are there horizontal lines on heating and cooling graphs?

Answer 5

Represent a change of state - energy is not used to heat up the substance, but to break the bonds and change state

Question 6

What is the formula for specific latent heat?

Answer 6

Energy transferred = mass * Slh
(kg) (J/kg)

Question 7

How does changing the temperature of a gas affect pressure?

Answer 7

Increases pressure:
Increases the energy and the kinetic energy of the collisions between the gas and container

Question 8

What is the pressure of a gas?

Answer 8

Due to the particles colliding with the container that the gas is held in. A small force is released upon collision, acting in right angles - causes pressure

Question 9

How can pressure be increased?

Answer 9

Increase no of collisions or increase energy of collisions

Question 10

How is the pressure of a gas related to its volume?

Answer 10

Smaller volume increases the gas pressure as the frequency of collisions is increased
pV = constant
(Pa) (m^3)
only applies if temp is constant